Impact of restriction of third generation cephalosporins on the burden of third generation cephalosporin resistant K. pneumoniae and E. coli in an ICU.

OBJECTIVE: To test whether a reduction of third generation cephalosporin (3GC) use has a sustainable positive impact on the high endemic prevalence of 3GC resistant K. pneumoniae and E. coli.

DESIGN: Segmented regression analysis of interrupted time series was used to analyse antibiotic consumption and resistance data 30 months before and 30 after the intervention.

SETTING: Surgical intensive care unit (ICU) with 16-bed unit in a teaching hospital.

INTERVENTION: In July 2004, 3GCs were switched to piperacillin in combination with a beta-lactamase-inhibitor as standard therapy for peritonitis and other intraabdominal infections.

RESULTS: Segmented regression analysis showed that the intervention achieved a significant and sustainable decrease in the use of 3GCs of -110.2 daily defined doses (DDD)/1,000 pd. 3GC use decreased from a level of 178.9 DDD/1,000 pd before to 68.7 DDD/1,000 pd after the intervention. The intervention resulted in a mean estimated reduction in total antibiotic use of 27%. Piperacillin/tazobactam showed a significant increase in level of 64.4 DDD/1,000 pd, and continued to increase by 2.3 DDD/1,000 pd per month after the intervention. The intervention was not associated with a significant change in the resistance densities of 3GC resistant K. pneumoniae and E. coli.

CONCLUSION: Reducing 3GCs does not necessarily impact positively on the resistance situation in the ICU setting. Likewise, replacing piperacillin with beta-lactamase inhibitor might provide a selection pressure on 3GC resistant E. coli and K. pneumoniae. To improve resistance, it might not be sufficient to restrict interventions to a risk area.